Re-fix ConsoleAppender

It turns out that calling `print` on `ConsoleOut` doesn't flush the
output. Remove `writeLine` and let `write` directly use `println`.

internal/util-logging/src/main/scala/sbt/internal/util/ConsoleAppender.scala

@@ -363,7 +363,7 @@ class ConsoleAppender private[ConsoleAppender] (
     out.lockObject.synchronized {
       message.lines.foreach { line =>
         val labeledLine = s"$RESET[${formatted(labelColor, label)}] ${formatted(messageColor, line)}"
-        writeLine(labeledLine)
+        write(labeledLine)
       }
     }
 
@@ -371,12 +371,9 @@ class ConsoleAppender private[ConsoleAppender] (
     val cleanedMsg =
       if (!useFormat) EscHelpers.removeEscapeSequences(msg)
       else msg
-    out.print(cleanedMsg)
+    out.println(cleanedMsg)
   }
 
-  private def writeLine(line: String): Unit =
-    write(line + EOL)
-
   private def appendMessage(level: Level.Value, msg: Message): Unit =
     msg match {
       case o: ObjectMessage         => objectToLines(o.getParameter) foreach { appendLog(level, _) }